The City Administrator shall execute and deliver all contracts for the City except contracts for an annual audit which shall be executed by the Mayor. Purchases may be made simultaneously with purchases by other governmental bodies and in cooperation with their officers. No purchase or contract in an amount more than authorized by state law shall be made except after advertisement and the receipt of bids in writing, except in the following cases: 1) emergency 2) use of state bidding process or 3) better value or performance, and in such case the City Administrator shall report the facts to the Mayor and to the Council at its next meeting. City Council shall have the right by ordinance or resolution to further restrict or increase the amount of purchases or contracts that may be authorized without bidding, but no increased limit shall exceed $75,000.